Gauge for airfoils



Sept 19, 1950 H. MILNER l 2,523,226

' GAUGE FOR AIRFOILS f' Filed Oct. 22, 1945 Patented Sept. 19, 1950Harry Lawley MilnerQCheltenham, England, assignor-to Rotol Limited,Gloucester, England,a

. British company v Application oetoberkzc, 1945, serial No. 623,819

` In Great Britain October 12 1943 w Section LlPblic'-lliaw 690, August8, 1946 l f Patentexpires 'October 12, 1963 f y' l 4Claims.

This invention relates togauges for aerofoils. and has for kits objectto provide a gauge Vof the type described in the specication ,of myapplical tion for United States Letters Patent Serial No. 464,087, nowPatent 2,402,567-granted 'June 2.5;. 1946, but which is simplerinconstruction and use, and of lighter weight. The improved-,gauge issuitable for use in theintegrating-,apparatus described in thespecificationofmy application for United States Letters Patent No.464,088, now Patent 2,400,942 granted May,28,1946 or the. modicationsthereof describedin thespecication of myapplication for UnitedStatesyLetters Patent Serial No. 623,818V v(corresponding to British No.16,751/43). 3,

According to this invention, the improved gauge comprises a main memberformed vwith an abutment to engage and be located/.bythe-,trailing edgeof the section of the blade at the station selected, a pairofscissor-members pivotally mounted on said member, contact-membersmounted adjustably on the long arms of said scissor-members, a pair of.links connected respectively to the short arms of said scissor-'membersand to a sleeve adapted to slide on the main y member aforesaidacompression spring operative on Said sleeve to close thearms ofsaidsc'isso'rr members, a nut screw-threaded Von the' main member toopen said scissor-members against the action of the spring, and asurfacej on said main member which bears a deiinite angularrelationship, for example is normal; tothe line Vbisecting the anglebetween the saidscissor-members'and passing through their pivot point,

In theaccompanying drawings which illustratel one embodiment of thisinvention, Figures 1"`and'2 are front and side elevations respectivelyfot the complete device.

Referring to the drawings, the main member of this gauge is ofcylindrical form as shown at 10, formed near one end with a shoulder 1Iand with a flat plate-like extension l2 beyond the shoulder. At the endof the part l2 there is formed a V-notch 13 to engage and be located bythe trailing edge of an airscrew-blade when the gauge is applied to it.The notch 13 does not extend with its apex straight across theplate-like part l2, but has its two ends sloped so as to providesubstantially point contact on the centre line of the member 10.

The other end of the member l is screwthreaded at 14 to receive a millednut 15 which is screw-threaded at 'I6 to engage the thread '14,v and isformed with a recess 1l to enable the nut when it is screwed down topass over the cylindrical part 10 if necessary,

On the end of the member 'Ill beyond the screw-threaded part 'I4 thereis rigidly secured a plate 96 which is formed with its upper surface 91accurately at right-angles to the longitudinal axis of the member; thisplate 99 is used to support an optical projection device resting orsecured on it. l

A pair of scissor-like elements 18, 'I9 are pivotally mounted one oneach side of the plate-like extension 'l2 by means of a pivot pin 89,and these members are cranked as shown at 8l, 82 in Fig-1' ure 2 so thattheirlonger members-v lie opposite one another. On leach of these armsthere is mounted a contact-member 83, 84 respectively so 15, as to beadjustable lengthwise ci therarm, being retained in any desired positionby locking screws 85, 88. These members 83, 84 carry rollers shownrespectively at 8l, 88 to engage the front and rear faces of the blade.rlhe short arms 89, 90 of the scissor-membersy 18, y'i9 which lie on theother-side of the pivot pin are connected by pivot links 9|, 92 to asleevemember r9i! which is slidable on the main member l0,A beingprevented from rotation thereon by a key 94 engaging a key-way 95. Acompression-spring 98 is mounted between the shoulder 'Il and the sleeve93 so as normally to force them apart, and by means of the links 9|, 92to press the rollers 81, 88 aforesaid towards one another. vThe positionof the sleeve 93 is adjusted by..means of the nut-member l5.

In the use of this device the nutmember 'l5 is turned so as to open outthe scissor-members 18, 19, and the gauge is then applied to an air-`screw-blade at the desiredrposition thereon. ,'Ihei contact-members 83,84 are 'adjusted so that Itherollers 8l, 8s engage the front and rearsurfaces of the blade at approximately the mid point of the chord ofthat section or" the blade to which they are applied, and the nut-memberl5 is then turned to close the rollers on to the blade. Since theserollers move at the same rate towards and away from one another, theaxial line of the -man member -which passes through the centre of theV-notch 13 aforesaid bisects the angle between the arms T8, 19 andtherefore passes through the point midway between the contact-members83, 84. This line then indicates with a considerable degree of accuracythe line of zero-lift at that section of the blade. The plate 96 whichis accurately at right-angles to this axial line therefore assumes acorresponding position, its angular setting with respect to some datumbeing indicated by the optical projection device which is mounted on theplate-member.

3 The above described construction of gauge offers the advantage thatthe clamping pressure of the contact-members on the surface of the bladeis eiected by the spring, and such pressure remains more or lessconstant forall stations alongv the blade, since with most forms ofairscrewblade, the thickest sections of the blade also have formsdescribed in my earlier specification afore-j said so that any tendencyfor the weight of the gauge to distort the blade is minimised.

Whilst this gauge is particularly suitable 'for use with the integratingapparatus above mentioried,` it is to be understood that it is notrestrictedl for' use therewith, since it may be used fordirectmeasurernent or" the angle of the zerolift lineby a suitableclinometer orvother. device attached to the plate-like portion on theend of4 the gauge.

I claim:

1. A. gauge foran airfoil comprising in combination, a mainmemberhavingone endV formedy with a V-notch-abutmentto engage andA to belocated onthe trailing edge of an airfoil, a pivot on said member spacedalong itI from said `abutment, a pair-of scissor-members hinged on saidpivot, each scissor member comprising along armvand ashort arm,whereof-the long arms extend from the pivotbeyond said abutmentsymmetrically about the line-joining the center of said pivot and bottomof the notch of said abutment, a contact-member on each longarm ad-.instable` therealong,` a sleeve slidable on said main member in thedirectionof the said line, a pair of links each connected at one endtosaid sleeve, and pivotally connected atv their other ends respectivelyto the shortarmsvof said scissor-members,` a nutscre'w-threaded on saidYmain member and engaging -saidf sleeve to adjust it therealong, and asurface-on said main member bearing a` definite angular relationshipwith thedirection of the line aforesaid joining thepivotand `'theabutment.

2. A gauge for an airfoil according to claim 1, including aY spring onthe main memberl pressing the said sleeve against the said nut in thedirection to close the long` arms towards oney another. v

3. A gauge for an airfoil according to claim' 1 having the said surfaceon the main member at right-angles to the line joining the said abutmentand the said pivotv on themember.

4. A gauge for an airfoil comprising in combination, a main memberhaving one end formed with a V-notch-abutment to engage and to belocated on the trailing edge of an airfoil, a pivot on` saidmemberspaced along it from said abutment, a pair of scissor-members hinged onsaid pivot, eachscissormember comprising a long arm and ashortarm,whereof the long arms eX- tend from the pivot beyond said abutmentsymvmetrically about the line joining the center of said pivot and thebottom of the notch of said abutment; acontact-member on each long armadjustable. therealong, a sleeve slidable on said main member in thedirection of the Vsaid line, a pair of-links each connected at one endto said sleeve, and pivotally connected at their other endsrespectivelyto the short arms of said scissor-members, a shoulder carried by saidmain member between said slidable sleeve and said pivotA spaced alongsaidm main member, and a spring slidable over said main member one endoiwhich abutsA said shoulder and the other end of whichv abutsvsaidsleeve for normally biasing said scissor members toa closed position,said main memberl having a keyway therein, said sleeve member having akeyway therein, a key in-said key-Way for yprohibiting rotationalmovement. oi" said slidable sleeve about said main member,anutscrew-threaded on said main member andfrengagin'gsaid sleeve toadjust it therealong, and a surface on said-main memberY bearingV adeinite angular' relationship with the directionof-thelinel-aforesaidljoining the pivotVv Thefollowingreferences are ofrecord in theY Y llez of: this. patentz..

UNITED STATESA PATENTS

